Cleaning device for vibrating screens



Nov. 15, 1960 J. J. ASSINCK ET AL 2,960,223

CLEANING DEVICE FOR VIBRATING SCREENS Filed Sept. 25, 1958 JOSEPH J. ASS/NCK ANTON B. ASS/NCK y WW Agent m 6E IT km KE m 7/4 T// v \K AM U S 3 Unite Joseph J. Assinck and Anton B. Assinck, both of Main Street, Markham, Ontario, Canada Filed Sept. 25, 1958, Ser. No. 763,336

1 Claim. (Cl. 209-390) This invention relates to a cleaning device for vibrating screens. It is particularly adapted to providing a brush assembly which is adapted to maintain the openings of the screen cloth clear of obstruction and clogging or blinding.

Vibrating screens are well known and are widely used for separating granular material of desired particle size from oversize or undersize particles or for classifying granular material according to the size of the particles.

There are a number of types of vibrating screens which are available to industry. In general, they may be divided into two distinct types, the mechanically actuated screen in which the screen frame is oscillated in a circular, elliptical or reciprocating motion by the rotation of an eccentrically mounted or unbalanced shaft assembly which carries the screen body, and the electrically driven screen in which the screen body of the screen cloth is vibrated States Patent ing description, reference being made to the accompanying drawing, in which:

Figure 1 is a perspective view of a vibrating screen which incorporates the cleaning device of this invention;

Figure 2 is an end View;

Figure 3 is a section taken along the line ZF-Z, Figure 1;

Figure 4 is a section taken along the line 4-4, Figure 3; and

Figure 5 is a perspective view of a self-cleaning pulley on which the conveyor is mounted.

Like reference characters refer to like parts throughout the description and the drawing.

The cleaning device of this invention is described as applied to an electrically actuated vibrating screen in which high speed vibrations are imparted by an elec-' tric motor or by magnetic impulses. Such screens vibrate in a plane vertical to the screen cloth, for example, a straight line movement of about 4 of an inch. The vibrations may be at a rate of from about 1,000 to 10,000 per minute. It will be understood, however, that the cleaning device can be applied to mechanically vibrated screens.

The vibrating screen illustrated in the drawing is a conventional electrically vibrated screen, such as that sold under the trademark Syntron and is comprised of a support frame 10 and side plates 11. Screen cloth 13 is carried by and is secured to the frame 10, being held in place along its longitudinal edges by the plates 14. The term screen cloth as used herein is intended to include woven or unwoven materials which are formed with openat high speed in a vertical plane by the action of an electric motor or by magnetic impulses. The cleaning device of this invention can be employed with advantage in the operation of both mechanically and electrically actuated vibrating screens.

The screen cloth usually is woven or otherwise formed of metal or fabric with holes or openings of a predetermined size. The size of the openings is, of course, determined by the size of the particles to be passed through the screen, the undersize fraction, and the size of the particles to be retained on the screen, the oversize fraction. The size of the screen openings may vary over a very wide range, for example, from three inches to 0.0015 inch, United States standard 400 mesh screen.

There is a problem in the operation of vibrating screens in that particles of the material being screened tend to become lodged in the screen openings and thus tend to close those openings to the passage of further particles with reduction in the capacity of the screen. This problem is particularly acute in screening wet or damp material and is progressively aggravated as the size of the screen openings is reduced.

We have found that this problem can be overcome by the provision of one or more brushes which are moved across the upper surface of the screen cloth. These brushes serve to distribute material to be screened relatively uniformly over the surface of the screen; they facilitate the passage of undersize material through the screen openings; and they dislodge any particles which may have become lodged in the screen openings.

The cleaning device for vibrating screens of this invention comprises, in general, a conveyor mounted for movement above the surface of the screen cloth and extending the length thereof, and at least one brush member carried by said conveyor and extending transversely thereof and of the width of said screen cloth, said brush being adapted to make contact with the upper surface of said screen cloth, and means for driving said conveyor.

An understanding of the cleaning device for vibrating screens of this invention can be obtained from the followings of specific sizes and used in screening operations. Usually the screen cloth is formed of woven.wire but for extremely fine sizing operations, other materials such as natural or synthetic fabric materials may be employed.

* Bars or rods 12. extend the length of the frame and are provided to stretch the screen cloth taut and impart a slight camber or curvature to it according to conventional practice. The screen cloth, or the entire frame are vibrated either electrically or mechanically according to 7 conventional practice by a conventional vibrating assembly which, as it forms no part of this invention, is not shown.

The screen frame, according to conventional practice, is carried on springs 50 to minimize the transmission of vibration to the screen supporting structure.

The conveyor 20 extends above the screen cloth and, preferably, the length thereof. As the only function of the conveyor is to carry the brushes 30, it can be formed of any suitable material. For example, it can be a conventional chain, rubber or fabric conveyor. It is of a width suflicient to provide a firm mounting for the brushes. The conveyor is of the endless type and is extended over pulleys 21-22 which are mounted on shafts 2324 respectively which extend transversely above the screen cloth 13 and are journalled in bearings 25-26 carried by the side plates ll. Pulley 2 1 is identified as the conveyor driving pulley and pulley 22 is identified as the tail pulley. The tail pulley 2 2 preferably is of the self-cleaning type as illustrated in Figure 5.

The shaft 2-3 is extended at one end, beyond the bearing 2.5 and a driving sheave or pulley 27 is mounted thereon. A motor 2% connected by a shaft 3 2 to a speed reducer 3 1 is mounted on a platform 29 which is secured to the plate 11 adjacent to the pulley 27. A belt 33 extends from the speed reducer 31 to the pulley 27. The speed reducer 3 1. can be adjusted, according to conventional practice, to drive the pulley 27' and the conveyor 20 at any predetermined speed.

The brush 30 is mounted in a frame comprised of spaced members 35 which are carried on a shaft or pedestal 36-. A base 3-7 is mounted transversely of the conveyor and is firmly secured thereto, such as by bolts 38. Spaced members 39 extend from the base 37 at right angles thereto. The shaft or pedestal 36 is received between these spaced members 39. The spaced members 39 or the shaft or pedestal 36 can be drilled at spaced inter vals and two parts secured together such as by a bolt and nut assembly 40 with the brush component 30 adjusted to make contact with the screen cloth.

The self-cleaning tail pulley 22 is provided to discharge from the machine any material which may collect on the underside of the conveyor belt. It is provided with an arrangement of angularly disposed, interior bafiies 5 1 which direct material which falls into the pulley to and out of the end.

In the operation of a vibrating screen assembly which embodies the cleaning device, of this invention, the conveyor belt 20 is driven at a speed at which maximum production is obtained from the screen. Usually, a plurality of brushes are mounted on the conveyor at spaced intervals so that at least one and preferably more than one brush is in contact with the surface of the screen cloth at all times.

The conveyor belt is relatively flexible so that the brushes, when properly adjusted, ride lightly on the screen cloth, thus to minimize the wear. The brush bristles can be formed of metal or other conventional material, natural or synthetic, as is used for such purposes. In the case of screen cloth in the form of drilled plates, bars and woven wire, metal bristles usually would be employed. If the screen cloth is in the form of woven fabric, bristles of softer material would be employed in the brushes.

We have found that the use of the cleaning device of this invention in the operation of vibrating screens has many important advantages. Heretofore, it has been very difiicult, if not impossible, to obtain a satisfactory rate of production in screening wet material, particularly wet, finely divided material such as brick clay, sand and the like. The cleaning device overcomes this problem to the extent that such material can be treated on a conventional four feet by eight feet electrically vibrated screen at a rate of fromv 150 to 2.00 tons per hour.

The production obtainable in the treatment of coarse, dry material also is increased substantially. Also, it is found that the useful life of the screen cloth is extended by the use of this device. In the use of a vibrating screen,

the strands between the screen openings wear and break to the extent that the screen cloth must be replaced. It may be that particles which become lodged in the screen openings cut or strain the strands which define the opening. It is found that when screen openings are kept clear of obstructions, the useful life of the screen cloth is extended.

It will be understood, of course, that modifications can be made in the preferred embodiment of this invention as described herein without departing from the scope of the invention defined by the appended claim.

What we claim as new and desire to protect by Letters Patent of the United States is:

In a vibrating screen comprising a frame, a screen carried by the frame, and means for vibrating said screen, the improvement in combination therewith which comprises a flexible, endless conveyor carried by spaced pulleys mounted above said screen and extending longitudinally thereof, means for driving said conveyor at a substantially uniform speed, at least one brush carried by said conveyor and extending transversely thereof and of a length substantially equivalent to the width of said screen, and means for adjusting the position of said brush in relation to the upper surface of said screen to bring it into light contact with the surface of the screen as it moves longitudinally thereof, comprising a base firmly secured and mounted transversely of the conveyor, said base comprising spaced members both extending at right angles to the base, said spaced members having complementary vertical elongated apertures therein, the brush having its non-contacting end enclosed in a U-shaped member having an apertured projection thereon enclosed by the spaced members of the base with detachable securing means through the apertures in the spaced member of the base and the projection on the U-shaped member adjustably supporting the brush.

References Cited in the file of this patent UNITED STATES PATENTS 417,836 Ponser Dec. 24, 1890 1,536,363 Ware May 5, 1925 2,510,741 Coon June 6, 1950 

